Integrated circuit (IC) products can be found in most electronic devices throughout the world. The most familiar applications of IC products are found in cellphones, camcorders, portable music players, televisions, and computers. Almost all of these product types employ some form of memory, whether as read-only memory (ROM), or random-access memory (RAM). ROM and RAM can also be classified as nonvolatile and volatile memory, respectively. Volatile memory is a semiconductor device that allows data to be stored and changed as desired; data in the volatile memory is lost when the power is turned off. Nonvolatile memory is a semiconductor device designed to store digital data in the form of an electrical charge, wherein the charge remains in storage even after the power is turned off.
Flash memory is a type of nonvolatile memory that can be erased and reprogrammed many times. Flash memory is usually constructed by one of two technologies, NOR-type or NAND-type. The names NOR (not OR) and NAND (not AND) refer to the type of logical functions used to program information within memory cells. Recently, NAND-type technology is considered to be a promising solution for not only nonvolatile stand alone memory, but also embedded memory due to its numerous aspects, such as, excellent scalability, low power consumption, process simplicity, and logic process compatibility.
The NAND-type flash memory array is formed by interconnecting flash memory cells in series with common-source/drain diffusion regions. The density of a NAND-type flash memory array is high, however the read speed is slow due to the series resistance of the configuration. Moreover, a NAND-type flash memory cell is programmed by Fowler-Nordheim tunneling, which characteristically displays a relatively slow programming speed.
Thus, a need still remains for a nonvolatile memory device with excellent scalability and low power consumption, that displays enhanced programming speed capacity. In view of the ever-increasing need to save costs and improve efficiencies, it is more and more critical that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.